Oxygen sensor problem
 

OK i have read about this exact problem here https://volvoforums.com/m_18180/tm.htm but the thread is inconclusive.

the story:
-car has a check engine light with the message window reading "emission system service required"
-i go to a volvo dealer to get the ETM recall software upgrade, dealer upgrades and tell me i have codes ECM-2910 and ECM-2B2A, both have several meanings in Vadis ( i just checked ) but they mean that front and rear bank 2 oxygen sensors are "bad"
-right away after leaving the dealer the check engine light comes back on within like 1 minute of driving but this time the message window says i have zero messages.
-i order 2 bosch sensors one for front and one for rear and have a buddy replace them both. he replaces them and uses a scanner to clear the code
-for one week all was good, but then the light would come on for half a day and then go away, this happen for about one week (intermittent every day or two) during this past week the light has been always on...
-i go back to the shop and have the car scanned, the codes are back saying both, front and rear bank 2 oxygen sensors are bad (by bad i mean the signal is low, high and non existent at the same time !!!
-mechanic connects a physical PC to the car with a cable and starts the car, he uses a program to PLOT the voltage on the oxygen sensors in question and as the sensors heat up they reach the proper operating value (meaning the sensor is functioning within its parameters - i watched him do it and i am convinced the results are correct)
-mechanic disconnects the battery and shorts the cables to drain the parasitic electricity...i drive home and no codes so far...

The questions:

1) mechanic says that the scanner can only RESET The light, not clear the code from memory becuse its a hard fault and the light trigger is still in the ECM. will taking the battery out/shorting cables reset this value or is this even true ?

2)dealer recommended replacement of all 4 oxygen sensors, to which my mechanic replied that on SOME cars with this many sensors the ECM may try to compare values from bank 1 to bank 2 and since the sensors that i did not replace may have carbon on them their values may be a little off, which triggers the MIL for the new sensors - this makes sense but why would the codes be set for the new sensors, should the code now switch to the old ones that a re dirty ? and if their values are within spec why would the ECM set the codes for them ?

Conclusion:

this is a problem seems to have been happening to people in the past so this is a common issue, the question is, after replacing the O2's why does the computer not see the new sensors as within spec ?

I will cross my fingers and hope the MIL will not come back on, but somehow i think that fighting with this car's computer is not over yet...

PS: the mech also looked for air leaks by spraying carb cleanig all over the hoses, while the scanner was connected and reading o2 values..values stayed the same all the time so no carb cleaner got inside through the hoses, when he sprayed the carb cleaning into the intake the values dipped but slowly came back up so that means i have no obvious air leaks...

RE: Oxygen sensor problem
 

I would also either unplug the battery or pull the fuse for the ECU for 15 minutes.
After the O2 sensors are replaced the ECU is supposed to be reset. Alot of times it takes the computer along time to see that the fault is fixed even after clearing the codes.

The adaptives are still to far off and take a while to get back to normal.

RE: Oxygen sensor problem
 

well so far so good, the battery disconnect and shortening seems to have done it so far, but then again when the code was reset the first time just with the scanner, it too dissapeared for a week and then later came back intermittently...

any idea why this is ? why does the scanner not fully reset the code ? not just on my car but seems to have on many cars before mine

RE: Oxygen sensor problem
 

His scanner doesn't read the Volvo correctly.

RE: Oxygen sensor problem
 

i hope you are right

RE: Oxygen sensor problem
 

Me to.

I know that aftermarket scanners don't read half of the stored codes and sometimes will not read any at all.

RE: Oxygen sensor problem
 

well i think he had a volvo scanner, it was called Vedis, (not vadis) that one was a large hand held one, he had two cables for it one is a volvo only and one is a generic cable, he also hooked up the car to a stand alone pc and used a program called Alldata so plot the voltage curve of the o2 and other things

i dont know, i have no control over this now, time will tell,, i will keep this thread updated if things change

RE: Oxygen sensor problem
 

Thanks for keeping up updated.

The only programs built for the Volvo's for Volvo cars was Vadis from 1998 till 2005 then they went to whats called VIDA.

RE: Oxygen sensor problem
 

Check engine light is back
i dont know what else to do .... this car is annoying

RE: Oxygen sensor problem
 

the check engine light turned off on the way home tonight, but i knwo it will come back

guys i just searched and found a few more threads regarding this same exact issue, a guy changed all 4 oxygen sensors to have the check engine light come back

ive been o nthe phone with 2 volvo dealers and remarcably they said their scanners are not going to reset this light so it never comes back, so it looks like its not the scanners, one private mechanic who deals with german imports told me to check for air leaks around the cat which i will try to look for on the weekend

this is not an isolated issue, this is a common issue there has to be a fix or at lease someone who knows whats causing this check engine light to come back after everything was fixed

RE: Oxygen sensor problem
 

Intake and exhaust leaks can cause it.

It is not as much of a problem as you think. Most of the time Bosch sensors fix it.

RE: Oxygen sensor problem
 

i used bosch on both front and rear

the car feels the same pretty much but i keep getting this thought in my head that my fuel mileage is a lot worse with that stupid light on, an air leak is a possibility, the mech checked the engine for air leaks , sprayed some stuff on all the hoses and monitored it but did not see anything, it is a possibility that the leaks is coming from the exhaust

i had a hole in an exhaust once on another car but the car sounded kinda loud, how can i find an exhaust leak thats not obvious ?

RE: Oxygen sensor problem
 

Usually you can hear exhaust leaks.
Also have him check for a leak while the car is under a Boost condition.

hasnt been on since i last posted, strange how it disappeared

Yes it is very strange.

o2 sensor p0133
 

I also have been having this problem. I have replaced everything I can think of in the air/fuel mixture system except for the Cat. I have used bosch or volvo parts. Still the cel comes back on showing slow response bank 1. Does anyone have an idea that works or has done something that worked?

Volvo S80 CheckEngine Light will not turn off
 

I changed both my forward oxygen sensors with the Bosch OEM made for this model and the check engine light went out for a while, but then a year later it is on again throwing a P0161 code. I can't get my registration renewed until I get this fixed and I have not been able to find a fix. I only put around 5K miles/year on the car, it has 108k and I think I put the sensors in at 104k. Any suggestions? BTW, how do you check for a leak around the Catalytic Converter? Could the Catalytic Converter be bad? Maybe that is the issue?

O2 sensor
 

I have apparently had the same problem. First I found an exhaust leak before the Upper Cat. next changed both sensors (Sparkplugs.com has the best price) then used premium gas. The light has stayed off for over 40K miles. However, it comes back on after just a few tanks of Regualr gas. Used premium and goes back out after a long drive (1hr) and passed the test.